The methods, arrangements and structures related to the above technical area and with a function and a character which meets the set requirements are previously known in various embodiments.
As an example of the background art and the technical area to which the invention pertains, one safety arrangement may be mentioned, being related to or integrally formed with a safety coupling, and coordinating with a safety mechanism, as disclosed in DE 40 28 158.
The safety coupling is actuatable by an adapted safety arrangement toward and into an initial active (retaining) position, or toward and into an inactive (releasing) position, with a connection to the above-described “on”/“off” function.
These torque transmission coupling units are adapted to, via rotary motion, allow for the transmission of (high) torque between a first, driving coupling member and a second, driven coupling member.
Said safety arrangement is adapted to, when a preselected torque and a relative motion caused by this high torque between the first and second coupling members are exceeded, be actuated, via a safety mechanism, in a displacement from its initial active position to its final inactive position, said safety arrangement being adapted to permit a limited relative movement between the first and the second coupling members corresponding to a selected maximized arcuate distance between its initial active position and its final inactive position, the safety arrangement being adapted to mechanically permit the coupling unit to be actuated to its inactive position by momentarily evacuating a cavity, filled with a medium under high pressure, of its contents (aqueous emulsion, oil).
It should be noted that a relative movement caused between the two coupling members over a friction surface located between the two coupling members can produce very high friction-related effects related to the prevailing frictional force and the length and width of the arcuate distance utilized for this purpose.
The known safety coupling, with its allocated safety mechanism, is constructed such that a limited relative movement between the coupling members, caused primarily by short-term torque peaks exceeding a predetermined maximized torque value, will be progressively utilized and added to each and every successive work cycle, until the chosen maximum arcuate distance is fully utilized and the final inactive position of the arrangement can be achieved with an extremely small final relative movement, less than the maximum arcuate distance, during one operating cycle.
The known safety coupling offers no visual inspection of, or easily ascertainable way of determining, the relative movement achieved between the coupling members at the start of each operating cycle.
When a safety coupling of the relevant kind has been triggered and assumed its final inactive (release) position, extensive measures are required to permit the safety coupling to re-activate, such that once a coupling unit has been triggered, such as in the form of a cut and opened valve assembly, a valve assembly must be replaced and a cavity in the safety coupling must be re-pressurized with an aqueous emulsion or oil via a replacement valve assembly.
These measures have proven to be extremely burdensome, especially in a situation where the safety coupling thus triggered, related to a drilling station, is located in an inaccessible place and position, such as high above a ground plane.
Therefore there is a need to develop improved safety couplings which solve the above problems.